1. Field of the Invention
The invention relates in general to an apparatus of generating optical tweezers, and more particularly to an apparatus of generating optical tweezers which can provide optical tweezers with momentum.
2. Description of the Related Art
The technology of “optical tweezers” for catching small particles or cells by using a gradient of a laser beam has existed. According to the conventional optical-tweezers technology, when a laser beam passes a diffractive optical element (DOE) with a phase-delay picture, the laser beam passing different parts of the phase-delay picture diffracts with each other to form a diffraction pattern which can be used to determine the gradient of the laser beam. The part of the diffraction pattern with higher light intensity has an effect of catching small particles.
However, the conventional optical-tweezers technology cannot provide the optical tweezers with transverse momentum (vertical to an optical axis) to shift the caught small particles. Therefore, the conventional optical-tweezers technology has to adjust a light modulator or use an extra push force for providing the optical tweezers with a momentum to shift the caught small particles.